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block: export dma_alignment attribute 

User space may want to know how to align their buffers to avoid
bouncing. Export the queue attribute.

Signed-off-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220610195830.3574005-4-kbusch@fb.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Keith Busch 2022-06-10 12:58:22 -07:00 committed by Jens Axboe
parent c58c0074c5
commit 3850e13f28
2 changed files with 16 additions and 0 deletions
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9
Documentation/ABI/stable/sysfs-block
View File

@ -260,6 +260,15 @@ Description:
for discards, and don't read this file.
What: /sys/block/<disk>/queue/dma_alignment
Date: May 2022
Contact: linux-block@vger.kernel.org
Description:
Reports the alignment that user space addresses must have to be
used for raw block device access with O_DIRECT and other driver
specific passthrough mechanisms.
What: /sys/block/<disk>/queue/fua
Date: May 2018
Contact: linux-block@vger.kernel.org

7
block/blk-sysfs.c
View File

@ -274,6 +274,11 @@ static ssize_t queue_virt_boundary_mask_show(struct request_queue *q, char *page
return queue_var_show(q->limits.virt_boundary_mask, page);
}
static ssize_t queue_dma_alignment_show(struct request_queue *q, char *page)
{
return queue_var_show(queue_dma_alignment(q), page);
}
#define QUEUE_SYSFS_BIT_FNS(name, flag, neg) \
static ssize_t \
queue_##name##_show(struct request_queue *q, char *page) \
@ -606,6 +611,7 @@ QUEUE_RO_ENTRY(queue_dax, "dax");
QUEUE_RW_ENTRY(queue_io_timeout, "io_timeout");
QUEUE_RW_ENTRY(queue_wb_lat, "wbt_lat_usec");
QUEUE_RO_ENTRY(queue_virt_boundary_mask, "virt_boundary_mask");
QUEUE_RO_ENTRY(queue_dma_alignment, "dma_alignment");
#ifdef CONFIG_BLK_DEV_THROTTLING_LOW
QUEUE_RW_ENTRY(blk_throtl_sample_time, "throttle_sample_time");
@ -667,6 +673,7 @@ static struct attribute *queue_attrs[] = {
&blk_throtl_sample_time_entry.attr,
#endif
&queue_virt_boundary_mask_entry.attr,
&queue_dma_alignment_entry.attr,
NULL,
};